Method of maintaining constant movement of a cutting blade of an ultrasonic waveguide

Abstract

A method of maintaining constant movement of a cutting blade of an ultrasonic waveguide includes the steps of providing an ultrasonic transducer operable to convert a received motional voltage into a movement of a cutting blade of an ultrasonic waveguide, a motional feedback circuit connected in a parallel configuration with the ultrasonic transducer, and a variable power source operable to apply a first voltage between a set of connection points to the parallel configuration. A feedback voltage measured from the motional feedback circuit is determined and an output of the power source is varied based upon the measured feedback voltage to result in a substantially constant feedback voltage and, thereby, maintain a substantially constant rate of movement of the cutting blade across a variety of cutting loads.

1. A method of maintaining constant movement of a cutting blade of an ultrasonic waveguide, which comprises:
 providing:
 an ultrasonic transducer operable to convert a received motional voltage into a movement of a cutting blade of an ultrasonic waveguide; 
 a first capacitive element in a series configuration with the ultrasonic transducer; 
 a motional feedback circuit connected in a parallel configuration with the ultrasonic transducer and comprising a second capacitive element and a third capacitive element in a series configuration with each other and, together, connected in a parallel configuration with the series configuration of the ultrasonic transducer and the first capacitive element, a capacitive value of the third capacitive element selected to be a fraction of a capacitive value of the ultrasonic transducer, the fraction having a value less than one, a capacitive value of the second capacitive element having a capacitive value of the first capacitive element multiplied by the fraction; and 
 a variable power source operable to apply a first voltage between a set of connection points to the parallel configuration; 
 
 determining a feedback voltage measured from the motional feedback circuit; and 
 varying an output of the power source based upon the measured feedback voltage to result in a substantially constant feedback voltage and, thereby, maintain a substantially constant rate of movement of the cutting blade across a variety of cutting loads. 
 
     
     
       2. The method according to  claim 1 , wherein the variable power source is connected in a parallel configuration with the series configuration of the transducer and the first capacitive element and with the series configuration of the second and third capacitive elements. 
     
     
       3. The method according to  claim 1 , which further comprises carrying out the determining step by measuring the feedback voltage from a first point located between the second and third capacitive elements and a second point located between the transducer and the first capacitive element. 
     
     
       4. The method according to  claim 1 , wherein the second and third capacitive elements have a combined capacitive value that is less than the first capacitive element. 
     
     
       5. The method according to  claim 1 , wherein a value of the motional voltage is a product of the fraction multiplied by the measured feedback voltage. 
     
     
       6. The method according to  claim 1 , which further comprises providing a voltage controller for carrying out the step of varying an output of the power source. 
     
     
       7. The method according to  claim 6 , wherein:
 the voltage controller comprises a processor; 
 the variable power source comprises a phase locked loop communicatively coupled to the processor, and which further comprises: 
 determining a frequency of movement of the cutting blade with the phase locked loop; and 
 utilizing the phase of the motional voltage to control the movement of the cutting blade such that the movement remains resonant along the ultrasonic waveguide. 
 
     
     
       8. The method according to  claim 1 , which further comprises:
 providing a clamping mechanism having a range of clamping force values and being operable to place material in physical contact with the cutting blade; 
 communicatively coupling the voltage controller to the clamping mechanism; and 
 varying the motional voltage with the voltage controller based upon a given clamping value within the range of clamping values. 
 
     
     
       9. The method according to  claim 1 , wherein the variable power source comprises a removable battery. 
     
     
       10. The method according to  claim 1 , which further comprises providing a disposable handle body with:
 a portion defining a battery-holding compartment having at least two battery contacts; 
 a waveguide attachment dock exposed to the environment and shaped to accept the ultrasonic waveguide therein; 
 a transducer attachment dock exposed to the environment and shaped to place the ultrasonic transducer in coaxial alignment with the ultrasonic waveguide when the ultrasonic waveguide is disposed within the waveguide attachment dock; and 
 an ultrasonic-signal-generator assembly dock exposed to the environment and shaped to substantially simultaneously:
 selectively removably secure at least the ultrasonic transducer to the handle body; 
 place an end of the ultrasonic transducer within the transducer attachment dock; and 
 electrically couple at least the ultrasonic transducer to the at least two battery contacts. 
 
 
     
     
       11. A method of maintaining constant movement of a cutting blade of an ultrasonic waveguide, which comprises:
 providing:
 an ultrasonic transducer operable to convert a received motional voltage into a movement of a cutting blade of an ultrasonic waveguide; 
 a first capacitive element in a series configuration with the ultrasonic transducer; 
 a second capacitive element and a third capacitive element in a series configuration with each other and, together, connected in a parallel configuration with the series configuration of the ultrasonic transducer and the first capacitive element, a capacitive value of the third capacitive element selected to be a fraction of a capacitive value of the ultrasonic transducer, the fraction having a value less than one, a capacitive value of the second capacitive element having a capacitive value of the first capacitive element multiplied by the fraction; and 
 a variable power source connected in a parallel configuration with:
 the series configuration of the ultrasonic transducer and the first capacitive element; and 
 the series configuration of the second and third capacitive elements, the variable power source operable to apply a first voltage between a set of connection points to the parallel configuration; 
 
 
 determining a feedback voltage measured from a first point located between the second and third capacitive elements and a second point located between the ultrasonic transducer and the first capacitive element; and 
 varying an output of the power source based upon the measured feedback voltage to result in a substantially constant feedback voltage and, thereby, maintain a substantially constant rate of movement of the cutting blade across a variety of cutting loads. 
 
     
     
       12. The method according to  claim 11 , wherein the second and third capacitive elements have a combined capacitive value that is less than the first capacitive element. 
     
     
       13. The method according to  claim 11 , wherein a value of the motional voltage is a product of the fraction multiplied by the measured feedback voltage. 
     
     
       14. The method according to  claim 11 , which further comprises providing a voltage controller for carrying out the step of varying an output of the power source. 
     
     
       15. The method according to  claim 14 , wherein:
 the voltage controller comprises a processor; 
 the variable power source comprises a phase locked loop communicatively coupled to the processor, and which further comprises: 
 determining a frequency of movement of the cutting blade with the phase locked loop; and 
 utilizing the phase of the motional voltage to control the movement of the cutting blade such that the movement remains resonant along the ultrasonic waveguide. 
 
     
     
       16. The method according to  claim 11 , which further comprises:
 providing a clamping mechanism having a range of clamping force values and being operable to place material in physical contact with the cutting blade; 
 communicatively coupling the voltage controller to the clamping mechanism; and 
 varying the motional voltage with the voltage controller based upon a given clamping value within the range of clamping values. 
 
     
     
       17. A method of maintaining constant movement of a cutting blade of an ultrasonic waveguide, which comprises:
 providing:
 an ultrasonic transducer operable to convert a received motional voltage into a movement of a cutting blade of an ultrasonic waveguide; 
 a removable battery; 
 a disposable handle body with:
 a portion defining a battery-holding compartment having at least two battery contacts; 
 a waveguide attachment dock exposed to the environment and shaped to accept the ultrasonic waveguide therein; 
 a transducer attachment dock exposed to the environment and shaped to place the ultrasonic transducer in coaxial alignment with the ultrasonic waveguide when the ultrasonic waveguide is disposed within the waveguide attachment dock; and 
 an ultrasonic-signal-generator assembly dock exposed to the environment and shaped to substantially simultaneously:
 selectively removably secure at least the ultrasonic transducer to the handle body; 
 place an end of the ultrasonic transducer within the transducer attachment dock; and 
 electrically couple at least the ultrasonic transducer to the at least two battery contacts; 
 
 
 a first capacitive element in a series configuration with the ultrasonic transducer; 
 a second capacitive element and a third capacitive element in a series configuration with each other and, together, connected in a parallel configuration with the series configuration of the ultrasonic transducer and the first capacitive element, a capacitive value of the third capacitive element selected to be a fraction of a capacitive value of the ultrasonic transducer, the fraction having a value less than one, a capacitive value of the second capacitive element having a capacitive value of the first capacitive element multiplied by the fraction; and 
 a variable power source connected in a parallel configuration with:
 the series configuration of the ultrasonic transducer and the first capacitive element; and 
 the series configuration of the second and third capacitive elements, the variable power source operable to apply a first voltage between a set of connection points to the parallel configuration; 
 
 
 determining a feedback voltage measured from a first point located between the second and third capacitive elements and a second point located between the ultrasonic transducer and the first capacitive element; and 
 varying an output of the power source based upon the measured feedback voltage to result in a substantially constant feedback voltage and, thereby, maintain a substantially constant rate of movement of the cutting blade across a variety of cutting loads. 
 
     
     
       18. The method according to  claim 17 , wherein the second and third capacitive elements have a combined capacitive value that is less than the first capacitive element. 
     
     
       19. The method according to  claim 17 , wherein a value of the motional voltage is a product of the fraction multiplied by the measured feedback voltage. 
     
     
       20. The method according to  claim 17 , which further comprises providing a voltage controller for carrying out the step of varying an output of the power source. 
     
     
       21. The method according to  claim 20 , wherein:
 the voltage controller comprises a processor; 
 the variable power source comprises a phase locked loop communicatively coupled to the processor, and which further comprises: 
 determining a frequency of movement of the cutting blade with the phase locked loop; and 
 utilizing the phase of the motional voltage to control the movement of the cutting blade such that the movement remains resonant along the ultrasonic waveguide. 
 
     
     
       22. The method according to  claim 17 , which further comprises:
 providing a clamping mechanism having a range of clamping force values and being operable to place material in physical contact with the cutting blade; 
 communicatively coupling the voltage controller to the clamping mechanism; and 
 varying the motional voltage with the voltage controller based upon a given clamping value within the range of clamping values.